1. Field of the Invention
The present invention relates to a silacyclopendadiene derivative, more specifically to a silacyclopendadiene derivative, an intermediate therefor and a process for producing the same.
2. Description of the Related Art
It has been tried in various ways in many laboratories to apply .pi.-electron series organic compounds to photo-functional materials or electron-functional materials. Among them, a group of .pi.-electron series organic compounds having a hetero 5-membered ring structure for a basic structure, for example, thiophene or pyrrole is known as one of the typical compound groups. However, a great part of these hetero 5-membered rings is electron-donative, and therefore the characteristic thereof has restricted the application to the materials. This has allowed electron-acceptive compounds to be required.
In recent years, it has been reported that a silacyclopentadiene ring in which a hetero atom is composed of silicon shows an electron-acceptive property, and application thereof to various functional materials is expected. It is reported in, for example, Japanese Patent Application Laid-Open Nos. Hei 6-100669 or Hei 6-166746 that application thereof to conductive polymers is intended. Further, examples in which silacyclopentadiene derivatives have been applied to organic EL elements are reported in The Chemical Society of Japan, 70 Spring Annual Meeting Pre-Manuscript II, pp. 700, 2D102 and pp. 701, 2D103; and 71 Autumn Annual Meeting Pre-Manuscript, pp. 32, 2P1.alpha.21 and pp. 32, 2P1.alpha.22.
When silacyclopentadiene derivatives are applied to such various functional materials, the introduction of various substituents into optional positions of the silacyclopentadiene rings according to purposes is related to controlling the quality of the compounds and therefore considered to be one of very important techniques for raising the performances of the functional materials.
Conventional synthetic methods for the silacyclopentadiene rings are restricted to specific ones as described in Chemical Review, vol. 90, pp. 215 to 263, 1990, and it has been impossible to freely synthesize various derivatives. Further, examples in which reactive substituents have been introduced into 2- and 5-positions of a silacyclopentadiene ring are shown in Japanese Patent Application Laid-Open Nos. Hei 7-179477 and Hei 7-300489, but the introduction has been restricted to the 2- and 5-positions.